Study On Fault Diagnosis For Wax Oil Hydrogenation Based On HYSYS Method

With refining heavy,high-sulfur crude oil and gasoline and diesel standards upgrading,hydrogenation technology has been widely used in refinery.Hydrotreating of second and third line of distillation wax can get high quality products,and can increase output of petrochemical raw material and middle distillates.However,wax oil hydrogenation unit operates under high temperature,high pressure and hydrogen present environment with the inflammable,explosive and toxic medium.According to GB50160-2008,hydrogenation device belongs to class A flammable and hazardous units.Therefore,we should focus on strengthening risk control and prevention of wax oil hydrogenation unit.So this article studied the following several aspects of wax oil hydrogenation unit:(1)Systematically using hazard and operability analysis(HAZOP)identifies hazards in the wax oil hydrogenation unit,and determine the risk rank with enterprise risk matrix.Considering enterprise common accident statistics and suggestions of on-site expertise,article selected "interruption of recycle hydrogen results in reactor overtemperature,rupture and leak causes fire and explosion","return tower overpressure and over temperature,equipment rupture and leak caused fire and explosion" accident scenarios to LOPA analysis.(2)Taking wax oil hydrogenation process of a certain enterprise for example,using the process simulation software HYSYS built steady and dynamic model of wax oil hydrogenation reaction part and fractionation part.Raw materials and products of wax oil hydrogenation process can be divided into raw material oil,diesel,kerosene,light and heavy naphtha,and gas.6 lumped reaction model was constructed.Simulation results are basically consistent with the actual result,meeting the demands of engineering design,which proved model constructed is reasonable and effective.(3)HAZOP analyzed fault reasons of fractionating column over temperature,HYSYS simulated those fault reasons and obtained different temperature variation trends,from which achieved fault diagnosis.(4)LOPA analysis results were incorporated into HYSYS simulation.It was concluded that when the main fractionator overhead backflow interrupted,feed temperature decreased from 328 ? to 298 ?,tower temperature was controlled stably at 159?;When one reflux interrupted,the main fractionator overhead temperature can be controlled within design criteria by lowering the feed temperature of 23 ?,or feed rate by 25%.